Does test pilot Michael Alsbury, who died last Friday in the crash of Virgin Galactic’s SpaceShipTwo rocket plane, count as a "fallen astronaut"? Alsbury’s death presents those who manage space memorials with a new challenge and a new opportunity. One could have seen it coming, but nobody seems to have expected it quite so soon.

Alsbury's biography certainly seems to match what the public expects out of an astronaut. He was on his ninth flight aboard the SpaceShipTwo vehicle called "VSS Enterprise," helping to test a rocket-powered craft that was designed to rise above the internationally recognized boundary of outer space,...